linux/mm
Andrea Arcangeli 880a99b60d mm/rmap: support move to different root anon_vma in folio_move_anon_rmap()
Patch series "userfaultfd move option", v6.

This patch series introduces UFFDIO_MOVE feature to userfaultfd, which has
long been implemented and maintained by Andrea in his local tree [1], but
was not upstreamed due to lack of use cases where this approach would be
better than allocating a new page and copying the contents.  Previous
upstraming attempts could be found at [6] and [7].

UFFDIO_COPY performs ~20% better than UFFDIO_MOVE when the application
needs pages to be allocated [2].  However, with UFFDIO_MOVE, if pages are
available (in userspace) for recycling, as is usually the case in heap
compaction algorithms, then we can avoid the page allocation and memcpy
(done by UFFDIO_COPY).  Also, since the pages are recycled in the
userspace, we avoid the need to release (via madvise) the pages back to
the kernel [3].  We see over 40% reduction (on a Google pixel 6 device) in
the compacting thread's completion time by using UFFDIO_MOVE vs. 
UFFDIO_COPY.  This was measured using a benchmark that emulates a heap
compaction implementation using userfaultfd (to allow concurrent accesses
by application threads).  More details of the usecase are explained in
[3].

Furthermore, UFFDIO_MOVE enables moving swapped-out pages without
touching them within the same vma. Today, it can only be done by mremap,
however it forces splitting the vma.

TODOs for follow-up improvements:
- cross-mm support. Known differences from single-mm and missing pieces:
	- memcg recharging (might need to isolate pages in the process)
	- mm counters
	- cross-mm deposit table moves
	- cross-mm test
	- document the address space where src and dest reside in struct
	  uffdio_move

- TLB flush batching.  Will require extensive changes to PTL locking in
  move_pages_pte().  OTOH that might let us reuse parts of mremap code.


This patch (of 5):

For now, folio_move_anon_rmap() was only used to move a folio to a
different anon_vma after fork(), whereby the root anon_vma stayed
unchanged.  For that, it was sufficient to hold the folio lock when
calling folio_move_anon_rmap().

However, we want to make use of folio_move_anon_rmap() to move folios
between VMAs that have a different root anon_vma.  As folio_referenced()
performs an RMAP walk without holding the folio lock but only holding the
anon_vma in read mode, holding the folio lock is insufficient.

When moving to an anon_vma with a different root anon_vma, we'll have to
hold both, the folio lock and the anon_vma lock in write mode. 
Consequently, whenever we succeeded in folio_lock_anon_vma_read() to
read-lock the anon_vma, we have to re-check if the mapping was changed in
the meantime.  If that was the case, we have to retry.

Note that folio_move_anon_rmap() must only be called if the anon page is
exclusive to a process, and must not be called on KSM folios.

This is a preparation for UFFDIO_MOVE, which will hold the folio lock, the
anon_vma lock in write mode, and the mmap_lock in read mode.

Link: https://lkml.kernel.org/r/20231206103702.3873743-1-surenb@google.com
Link: https://lkml.kernel.org/r/20231206103702.3873743-2-surenb@google.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: kernel-team@android.com
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Nicolas Geoffray <ngeoffray@google.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: ZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-12-29 11:58:23 -08:00
..
damon mm/damon/core-test: test max_nr_accesses overflow caused divide-by-zero 2023-12-20 14:48:13 -08:00
kasan sync mm-stable with mm-hotfixes-stable to pick up depended-upon changes 2023-12-20 14:47:18 -08:00
kfence LoongArch changes for v6.6 2023-09-08 12:16:52 -07:00
kmsan kmsan: use stack_depot_save instead of __stack_depot_save 2023-12-10 16:51:46 -08:00
backing-dev.c writeback: remove redundant checks for root memcg 2023-08-21 13:37:48 -07:00
balloon_compaction.c
bootmem_info.c bootmem: use kmemleak_free_part_phys in put_page_bootmem 2023-10-25 16:47:13 -07:00
cma_debug.c
cma_sysfs.c
cma.c mm: cma: remove unnecessary initialization of ret 2023-12-12 10:57:08 -08:00
cma.h
compaction.c mm: compaction: avoid fast_isolate_freepages blindly choose improper pageblock 2023-12-12 10:57:08 -08:00
debug_page_alloc.c mm: page_alloc: split out DEBUG_PAGEALLOC 2023-06-09 16:25:23 -07:00
debug_page_ref.c
debug_vm_pgtable.c mm: fix multiple typos in multiple files 2023-10-25 16:47:14 -07:00
debug.c mm: update validate_mm() to use vma iterator 2023-06-09 16:25:31 -07:00
dmapool_test.c dmapool: add alloc/free performance test 2023-04-05 19:42:38 -07:00
dmapool.c dmapool: create/destroy cleanup 2023-06-09 16:25:17 -07:00
early_ioremap.c mm/early_ioremap.c: improve the execution efficiency of early_ioremap_setup() 2023-06-09 16:25:56 -07:00
fadvise.c mm: remove unnecessary pagevec includes 2023-06-23 16:59:31 -07:00
fail_page_alloc.c mm: page_alloc: split out FAIL_PAGE_ALLOC 2023-06-09 16:25:23 -07:00
failslab.c
filemap.c sync mm-stable with mm-hotfixes-stable to pick up depended-upon changes 2023-12-20 14:47:18 -08:00
folio-compat.c mm: return void from folio_start_writeback() and related functions 2023-12-10 16:51:37 -08:00
gup_test.c Merge mm-hotfixes-stable into mm-stable to pick up depended-upon changes. 2023-06-23 16:58:19 -07:00
gup_test.h
gup.c mm/gup: fix follow_devmap_p[mu]d() on page==NULL handling 2023-12-10 16:51:52 -08:00
highmem.c mm: ptep_get() conversion 2023-06-19 16:19:25 -07:00
hmm.c mm: enable page walking API to lock vmas during the walk 2023-08-21 13:07:20 -07:00
huge_memory.c mm: thp: introduce multi-size THP sysfs interface 2023-12-20 14:48:12 -08:00
hugetlb_cgroup.c mm, hugetlb: remove HUGETLB_CGROUP_MIN_ORDER 2023-10-18 14:34:17 -07:00
hugetlb_vmemmap.c mm: hugetlb_vmemmap: move mmap lock to vmemmap_remap_range() 2023-12-12 10:57:08 -08:00
hugetlb_vmemmap.h mm: hugetlb_vmemmap: fix reference to nonexistent file 2023-10-25 16:47:14 -07:00
hugetlb.c hugetlb: fix null-ptr-deref in hugetlb_vma_lock_write 2023-12-06 16:12:43 -08:00
hwpoison-inject.c
init-mm.c mm: move dummy_vm_ops out of a header 2023-08-21 13:37:46 -07:00
internal.h mm: use vma_pages() for vma objects 2023-12-12 10:57:08 -08:00
interval_tree.c
io-mapping.c
ioremap.c mm: ioremap: remove unneeded ioremap_allowed and iounmap_allowed 2023-08-18 10:12:36 -07:00
Kconfig mm/thp: add CONFIG_TRANSPARENT_HUGEPAGE_NEVER option 2023-12-12 10:57:07 -08:00
Kconfig.debug mm: page_table_check: Make it dependent on EXCLUSIVE_SYSTEM_RAM 2023-05-29 16:14:28 +01:00
khugepaged.c mm: thp: introduce multi-size THP sysfs interface 2023-12-20 14:48:12 -08:00
kmemleak.c kmemleak: avoid RCU stalls when freeing metadata for per-CPU pointers 2023-12-12 10:57:07 -08:00
ksm.c mm: ksm: remove unnecessary try_to_freeze() 2023-12-20 14:48:13 -08:00
list_lru.c mm/list_lru.c: remove unused list_lru_from_kmem() 2023-12-20 14:48:11 -08:00
maccess.c mm: Fix copy_from_user_nofault(). 2023-04-12 17:36:23 -07:00
madvise.c mm/madvise: add cond_resched() in madvise_cold_or_pageout_pte_range() 2023-12-06 16:12:50 -08:00
Makefile mm: vmscan: move shrinker-related code into a separate file 2023-10-04 10:32:23 -07:00
mapping_dirty_helpers.c mm: fix clean_record_shared_mapping_range kernel-doc 2023-08-24 16:20:30 -07:00
memblock.c NUMA: optimize detection of memory with no node id assigned by firmware 2023-12-10 16:51:34 -08:00
memcontrol.c mm: memcg: restore subtree stats flushing 2023-12-20 14:48:11 -08:00
memfd.c memfd: drop warning for missing exec-related flags 2023-10-04 10:32:22 -07:00
memory_hotplug.c mm/memory_hotplug: split memmap_on_memory requests across memblocks 2023-12-10 16:51:34 -08:00
memory-failure.c sync mm-stable with mm-hotfixes-stable to pick up depended-upon changes 2023-12-20 14:47:18 -08:00
memory-tiers.c dax, kmem: calculate abstract distance with general interface 2023-10-16 15:44:39 -07:00
memory.c mm/memory: replace kmap() with kmap_local_page() 2023-12-20 14:48:14 -08:00
mempolicy.c Many singleton patches against the MM code. The patch series which are 2023-11-02 19:38:47 -10:00
mempool.c mm/mempool: replace kmap_atomic() with kmap_local_page() 2023-12-10 16:51:49 -08:00
memremap.c mm: use vmem_altmap code without CONFIG_ZONE_DEVICE 2023-12-10 16:51:48 -08:00
memtest.c mm: memtest: convert to memtest_report_meminfo() 2023-08-21 13:37:47 -07:00
migrate_device.c Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
migrate.c mm: migrate high-order folios in swap cache correctly 2023-12-20 13:46:19 -08:00
mincore.c mm: enable page walking API to lock vmas during the walk 2023-08-21 13:07:20 -07:00
mlock.c mm: mlock: avoid folio_within_range() on KSM pages 2023-10-25 16:47:14 -07:00
mm_init.c mm/mm_init.c: append newline to the unavailable ranges log-message 2023-12-10 16:51:51 -08:00
mm_slot.h
mmap_lock.c
mmap.c mmap: remove the IA64-specific vma expansion implementation 2023-12-10 16:51:39 -08:00
mmu_gather.c mm: fix kernel-doc warning from tlb_flush_rmaps() 2023-08-24 16:20:30 -07:00
mmu_notifier.c mmu_notifiers: rename invalidate_range notifier 2023-08-18 10:12:41 -07:00
mmzone.c zswap: shrink zswap pool based on memory pressure 2023-12-12 10:57:02 -08:00
mprotect.c mm: mprotect: use a folio in change_pte_range() 2023-10-25 16:47:12 -07:00
mremap.c mm: abstract VMA merge and extend into vma_merge_extend() helper 2023-10-18 14:34:18 -07:00
msync.c
nommu.c Many singleton patches against the MM code. The patch series which are 2023-11-02 19:38:47 -10:00
oom_kill.c mm, oom:dump_tasks add rss detailed information printing 2023-12-10 16:51:53 -08:00
page_alloc.c mm: page_alloc: simplify __free_pages_ok() 2023-12-20 14:48:14 -08:00
page_counter.c
page_ext.c mm/page_ext: move functions around for minor cleanups to page_ext 2023-08-18 10:12:31 -07:00
page_idle.c
page_io.c mm: memcg: add THP swap out info for anonymous reclaim 2023-10-04 10:32:27 -07:00
page_isolation.c mm/hugetlb: get rid of page_hstate() 2023-08-18 10:12:39 -07:00
page_owner.c mm/page_owner: record and dump free_pid and free_tgid 2023-12-10 16:51:40 -08:00
page_poison.c mm/page_poison: replace kmap_atomic() with kmap_local_page() 2023-12-10 16:51:50 -08:00
page_reporting.c mm, treewide: redefine MAX_ORDER sanely 2023-04-05 19:42:46 -07:00
page_reporting.h
page_table_check.c mm: convert page_table_check_pte_set() to page_table_check_ptes_set() 2023-08-24 16:20:18 -07:00
page_vma_mapped.c mm: thp: introduce multi-size THP sysfs interface 2023-12-20 14:48:12 -08:00
page-writeback.c mm: return void from folio_start_writeback() and related functions 2023-12-10 16:51:37 -08:00
pagewalk.c mm: pagewalk: assert write mmap lock only for walking the user page tables 2023-12-10 16:51:53 -08:00
percpu-internal.h percpu-internal/pcpu_chunk: re-layout pcpu_chunk structure to reduce false sharing 2023-06-19 16:19:29 -07:00
percpu-km.c
percpu-stats.c
percpu-vm.c
percpu.c Many singleton patches against the MM code. The patch series which are 2023-11-02 19:38:47 -10:00
pgalloc-track.h
pgtable-generic.c mm/pgtable: notes on pte_offset_map[_lock]() 2023-08-18 10:12:25 -07:00
process_vm_access.c mm: fix process_vm_rw page counts 2023-12-10 16:51:39 -08:00
ptdump.c mm: ptdump should use ptep_get_lockless() 2023-06-19 16:19:24 -07:00
readahead.c mm/readahead: do not allow order-1 folio 2023-12-12 10:57:06 -08:00
rmap.c mm/rmap: support move to different root anon_vma in folio_move_anon_rmap() 2023-12-29 11:58:23 -08:00
rodata_test.c
secretmem.c mm/secretmem: use a folio in secretmem_fault() 2023-08-21 13:38:02 -07:00
shmem_quota.c shmem: Add default quota limit mount options 2023-08-09 09:15:40 +02:00
shmem.c sync mm-stable with mm-hotfixes-stable to pick up depended-upon changes 2023-12-20 14:47:18 -08:00
show_mem.c mm: refactor si_mem_available() 2023-10-04 10:32:19 -07:00
shrinker_debug.c mm: shrinker: convert shrinker_rwsem to mutex 2023-10-04 10:32:26 -07:00
shrinker.c mm: shrinker: convert shrinker_rwsem to mutex 2023-10-04 10:32:26 -07:00
shuffle.c
shuffle.h mm, treewide: redefine MAX_ORDER sanely 2023-04-05 19:42:46 -07:00
slab_common.c RCU pull request for v6.7 2023-10-30 18:01:41 -10:00
slab.c Randomized slab caches for kmalloc() 2023-07-18 10:07:47 +02:00
slab.h mm: kmem: scoped objcg protection 2023-10-25 16:47:11 -07:00
slub.c slub, kasan: improve interaction of KASAN and slub_debug poisoning 2023-12-10 16:51:48 -08:00
sparse-vmemmap.c mm/vmemmap: allow architectures to override how vmemmap optimization works 2023-08-18 10:12:53 -07:00
sparse.c mm/sparse: remove redundant judgments from macro for_each_present_section_nr 2023-08-18 10:12:14 -07:00
swap_cgroup.c
swap_slots.c
swap_state.c zswap: shrink zswap pool based on memory pressure 2023-12-12 10:57:02 -08:00
swap.c mm: remove references to pagevec 2023-06-23 16:59:30 -07:00
swap.h zswap: make shrinking memcg-aware 2023-12-12 10:57:01 -08:00
swapfile.c mm/swapfile: replace kmap_atomic() with kmap_local_page() 2023-12-10 16:51:53 -08:00
truncate.c fs: convert error_remove_page to error_remove_folio 2023-12-10 16:51:42 -08:00
usercopy.c mm: Fix copy_from_user_nofault(). 2023-04-12 17:36:23 -07:00
userfaultfd.c mm: more ptep_get() conversion 2023-11-15 15:30:09 -08:00
util.c mm/util: use kmap_local_page() in memcmp_pages() 2023-12-10 16:51:49 -08:00
vmalloc.c mm/vmalloc: fix the unchecked dereference warning in vread_iter() 2023-11-01 12:38:35 -07:00
vmpressure.c net-memcg: Fix scope of sockmem pressure indicators 2023-08-16 12:21:32 +01:00
vmscan.c mm: memcg: restore subtree stats flushing 2023-12-20 14:48:11 -08:00
vmstat.c mm: memcg: add per-memcg zswap writeback stat 2023-12-12 10:57:02 -08:00
workingset.c mm: memcg: restore subtree stats flushing 2023-12-20 14:48:11 -08:00
z3fold.c mm/z3fold: remove obsolete comment for struct z3fold_pool 2023-08-21 13:37:51 -07:00
zbud.c mm: zswap: remove shrink from zpool interface 2023-06-19 16:19:27 -07:00
zpool.c mm: zswap: remove shrink from zpool interface 2023-06-19 16:19:27 -07:00
zsmalloc.c zsmalloc: use copy_page for full page copy 2023-10-18 14:34:16 -07:00
zswap.c mm: memcg: restore subtree stats flushing 2023-12-20 14:48:11 -08:00